替換所有非標題行中特定列的值

Question

下面是一些運行在與此類似的文件（old_file.csv）上的python代碼。

A,B,C,D 
1,2,XX,3 
11,22,XX,33 
111,222,XX,333 

如何可以通過在old_file.csv所有行迭代（如果不知道該文件的長度），並在列C或索引2或細胞[行]替換所有值[2] （基於單元格[row] [col]）。但我想忽略標題行。在new_file.csv中，包含'XX'的所有值都將變成'YY'。

import csv 
r = csv.reader(open('old_file.csv')) 
cells = [l for l in r] 
cells[1][2] = 'YY' 
cells[2][2] = 'YY' 
cells[3][2] = 'YY' 
w = csv.writer(open('new_file.csv', 'wb')) 
w.writerows(cells) 

Answer 1

在@Soviut ANS只是小改，試試這個我認爲這將有助於你

import csv 

rows = csv.reader(open('old_file.csv')) 
newRows=[] 
for i, row in enumerate(rows): 
    # ignore the first row, modify all the rest 
    if i > 0: 
     row[2] = 'YY'  
    newRows.append(row) 
# write rows to new CSV file, no header is written unless explicitly told to 
w = csv.writer(open('new_file.csv', 'wb')) 
w.writerows(newRows) 

Answer 2

CSV讀者使得陣列，所以你可以只在r[1:]

Answer 3

len(cells)運行它的行數。從1開始迭代使其跳過標題行。 lines也應該是cells。

import csv 
    r = csv.reader(open('old_file.csv')) 
    cells = [l for l in r] 
    for i in range(1, len(cells)): 
     cells[i][2] = 'YY' 
    w = csv.writer(open('new_file.csv', 'wb')) 
    w.writerows(cells) 

Answer 4

您可以非常容易地遍歷行數組並替換目標單元格中​​的值。

# get rows from old CSV file 
rows = csv.reader(open('old_file.csv')) 

# iterate over each row and replace target cell 
for i, row in enumerate(rows): 
    # ignore the first row, modify all the rest 
    if i > 0: 
     row[2] = 'YY' 

# write rows to new CSV file, no header is written unless explicitly told to 
w = csv.writer(open('new_file.csv', 'wb')) 
w.writerows(rows) 

Answer 5

read_handle = open('old_file.csv', 'r') 
data = read_handle.read().split('\n') 
read_handle.close() 
new_data = [] 
new_data.append(data[0]) 
for line in data[1:]: 
    if not line: 
     new_data.append(line) 
     continue 
    line = line.split(',') 
    line[2] = 'YY' 
    new_data.append(','.join(line)) 
write_handle = open('new_file.csv', 'w') 
write_handle.writelines('\n'.join(new_data)) 
write_handle.close()